According to the study, Brockman and associates conducted a series of five experiments in which subjects were shown pictures of people on a computer screen. The subjects were asked if the people on the screen were holding a gun or something more neutral, such as a cell phone or can of soda. These subjects responded to these tests while holding either a toy gun or a neutral object, such as a foam ball.

In an attempt to vary the results, the researchers adjusted the situation in each experiment. For example, in some of the experiments the people in the images were wearing ski masks. The researchers also varied the race of the people in the images and asked the subjects to adjust their reactions when they perceived the people to be holding a gun.

The results were unwavering despite the changing situations: The subjects were more likely to report, “gun present” when they themselves were holding a gun than when they were holding the foam ball. The subjects were also more likely to classify more objects in the images as guns and subsequently engage in threat-induced behavior, such as raising the gun to shoot.

“Beliefs, expectations, and emotions can all influence an observer´s ability to detect and to categorize objects as guns,” Dr. Brockmole says. “Now we know that a person´s ability to act in certain ways can bias their recognition of objects as well, and in dramatic ways. It seems that people have a hard time separating their thoughts about what they perceive and their thoughts about how they can or should act.”

The researchers also found that actually holding a gun was a key factor in the results. The subjects could know that a gun was in the room with them without affecting the results. It wasn´t until the gun was in the subject´s hands that their perception was changed.

“One reason we supposed that wielding a firearm might influence object categorization stems from previous research in this area which argues that people perceive the spatial properties of their surrounding environment in terms of their ability to perform an intended action,” Brockmole says.

This new study backs up other research that suggested people with broad shoulders perceived doorways to be narrower and softball players with a higher batting average to perceive the ball to be larger. This research, combined with Brockmole´s, suggests that people are more likely to let their surroundings affect their perceptions.

“In addition to the theoretical implications for event perception and object identification, these findings have practical implications for law enforcement and public safety,” Brockmole says.